In industry generally, there is a continuing need to produce compounds that are environmentally safe. The U.S. Environmental Protection Agency (EPA) is concerned with reducing the use of toxic chemicals that the EPA considers to be unsafe environmentally. In particular, in association with their 33/50 Program, the EPA has placed a high priority on reducing the presence of 17 toxic chemicals in the environment. These chemicals are published in a list ("the EPA 17 Toxics list") that includes benzene, cadmium and cadmium compounds, carbon tetrachloride, chloroform, chromium and chromium compounds, cyanides, lead and lead compounds, mercury and mercury compounds, methyl ethyl ketone, methyl isobutyl ketone, methylene chloride, nickel and nickel compounds, tetrachloroethylene, toluene, trichloroethylene, trichloroethane and xylenes.
One area where the use of environmentally safe compounds is important is the solvent industry. At one time, the preferred cleaning solvent for the aircraft and aerospace industry was methylene chloride. However, for environmental reasons, it has become less desirable for use in solvent compositions. One replacement for methylene chloride has been 1,1,1-trichloroethane (methyl chloroform). But, like methylene chloride, 1,1,1-trichloroethane is not considered environmentally safe. Moreover, 1,1,1-trichloroethane is not as effective a solvent as methylene chloride.
There has been a need in the art to provide new cleaning solvents that are not only effective but also environmentally safe. In the aircraft and aerospace industry recently, the solvents used to clean composites, metal aircraft parts and tooling include methyl ethyl ketone (MEK), toluene, methyl isobutyl ketone (MIBK), and combinations thereof. However, like methylene chloride and 1,1,1-trichloroethane, these compounds are not considered environmentally safe and have been listed on the EPA 17 Toxics list. In addition, the use of toluene must be reported under California law because of its reproductive toxicity. Therefore, there is a need in the art to produce solvent compositions with increased environmental safety that are effective at cleaning metal and non-metal surfaces.